Source: Richard Glickman-Simon, MD, Assistant Professor, Department of Public Health and Community Medicine, Tufts University School of Medicine, MA

This video describes the examination of the ear, beginning with a review of its surface and interior anatomy (Figure 1). The cartilaginous auricle consists of the helix, antihelix, earlobe, and tragus. The mastoid process is positioned just behind the earlobe. The slightly curving auditory canal ends at the tympanic membrane, which transmits sound waves collected by the external ear to the air-filled middle ear. The Eustachian tube connects to the middle ear with the nasopharynx. Vibrations of the tympanic membrane transmit to the three connected ossicles of the middle ear (the malleus, incus, and stapes). The vibrations are transformed into electrical signals in the inner ear, and then carried to the brain by the cochlear nerve. Hearing, therefore, comprises a conductive phase that involves the external and middle ear, and a sensorineural phase that involves the inner ear and cochlear nerve.
The auditory canal and the tympanic membrane are examined with the otoscope, a handheld instrument with a light source, a magnifier, and a disposable cone-shaped speculum. It is important to be familiar with the tympanic membrane landmarks (…

1Department of Integrative Physiology, National Institute for Physiological Sciences, 2Department of Otolaryngology, Head and Neck Surgery, Nagoya City University Graduate School of Medical Sciences and Medical School, 3Department of Otorhinolaryngology, Kansai Rosai Hospital, 4Institute for Biomagnetism and Biosignalanalysis, University of Muenster, 5Institute for Epidemiology and Social Medicine, University of Muenster, 6Sokendai Graduate University for Advanced Studies

1Department of Ophthalmology, UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, University of Pittsburgh School of Medicine, 2Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, 3The McGowan Institute for Regenerative Medicine, University of Pittsburgh School of Medicine, 4Deptartment of Biostatistics, Graduate School of Public Health, University of Pittsburgh

The collection of blood from mice and rats for analysis can be done through a variety of methods. Each method of collection has variations in the type of restraint required, the invasiveness of the procedure, and the necessity of a general anesthetic.1Historically, the use of the retro-orbital sinus cavity has been used, but not without debate. The controversy related to the potential tissue damage,or even blindness,caused by retro-orbital bleeds has led to the development of facial and submandibular vein bleeding methods in mice.Blood collection from the saphenous vein in both mice and rats is another technique that has been developed. These procedures do not require anesthesia and therefore are suitable when the use of anesthetics may confound blood results or other data.
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1Anatomy and Cell Biology, Indiana University School of Medicine, 2Research and Development Services, Richard L. Roudebush VA Medical Center, 3Department of Anatomy and Cell Biology, University of Illinois, Chicago

The cranial nerve (CN) examination follows the mental status evaluation in a neurological exam. However, the examination of the cranial nerves begins with observations made upon greeting the patient. For example, weakness of the facial muscles that are innervated by the cranial nerve VII can be readily apparent during the first encounter with the patient. Cranial nerve VII, the Facial nerve, also has sensory branches, which innervate the taste buds on the anterior two-thirds of the tongue and the medial aspect of the external auditory canal. Therefore, finding ipsilateral taste dysfunction in the patient with facial weakness confirms the involvement of CN VII. In addition, knowledge of the neuroanatomy helps the clinician to localize level of the lesion: unilateral weakness of the lower facial muscles suggests a supranuclear lesion on the opposite side, while lesions involving the nuclear or infranuclear portion of the facial nerve, manifest with an ipsilateral paralysis of all the facial muscles on the involved side.
Cranial nerve VIII, the Acoustic nerve, has two divisions: the hearing (cochlear) division, and the vestibular division, which innervates the semicirc…

1Department of Physiology and Pharmacology, University of Western Ontario, 2Department of Psychology, University of Western Ontario, 3Department of Medical Biophysics, University of Western Ontario, 4Brain and Mind Institute, University of Western Ontario, 5Centre for Functional and Metabolic Mapping, Robarts Research Institute, University of Western Ontario, 6Cerebral Systems Laboratory, University of Western Ontario, 7National Centre for Audiology, University of Western Ontario

1Department of Orthodontics and Craniofacial Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 2Department of Biological Structure, University of Washington School of Medicine, 3Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center

During each section of the neurological testing the examiner uses the powers of observation to assess the patient. In some cases cranial nerve dysfunction is readily apparent: a patient might mention a characteristic chief complaint (such as loss of smell or diplopia), or a visually evident physical sign of cranial nerve involvement, such as in facial nerve palsy. However, in many cases a patient's history doesn't directly suggest cranial nerve pathologies, as some of them (such as sixth nerve palsy) may have subtle manifestations and can only be uncovered by a careful neurological exam. Importantly, a variety of pathological conditions that are associated with alterations in mental status (such as some neurodegenerative disorders or brain lesions) can also cause cranial nerve dysfunction, therefore any abnormal findings during a mental status exam should prompt a careful and complete neurological exam.
The cranial nerve examination is applied neuroanatomy. The cranial nerves are symmetrical, therefore while performing the examination each side should be compared to the other. A physician should approach the examination in a systematic fashion and go through the …

Source: Richard Glickman-Simon, MD, Assistant Professor, Department of Public Health and Community Medicine, Tufts University School of Medicine, MA

The lymphatic system has two main functions: to return extracellular fluid back to the venous circulation and to expose antigenic substances to the immune system. As the collected fluid passes through lymphatic channels on its way back to the systemic circulation, it encounters multiple nodes consisting of highly concentrated clusters of lymphocytes. Most lymph channels and nodes reside deep within the body and, therefore, are not accessible to physical exam (Figure 1). Only nodes near the surface can be inspected or palpated. Lymph nodes are normally invisible, and smaller nodes are also non-palpable. However, larger nodes (>1 cm) in the neck, axillae, and inguinal areas are often detectable as soft, smooth, movable, non-tender, bean-shaped masses imbedded in subcutaneous tissue.
Lymphadenopathy usually indicates an infection or, less commonly, a cancer in the area of lymph drainage. Nodes may become enlarged, fixed, firm, and/or tender depending on the pathology present. For example, a soft, tender lymph node palpable near the angle of the mandible may indicate an infected tonsil, whereas a firm, enlarged, non-tender lymph …

Examination of the neck can be a challenge because of the many bones, joints, and ligaments that make up the underlying cervical spine. The cervical spine is composed of seven vertebrae stacked in gentle C-shaped curve. The anterior part of each vertebra is made up of the thick bony body, which is linked to the body above and below by intervertebral discs. These discs help provide stability and shock absorption to the cervical spine. The posterior elements of the vertebra, which include the laminae, transverse, and spinous processes and the facet joints, form a protective canal for the cervical spinal cord and its nerve roots.
The cervical spine supports the head and protects the neural elements as they come from the brain and from the spinal cord. Therefore, injuries or disorders affecting the neck can also affect the underlying spinal cord and have potentially catastrophic consequences. The significant motion that occurs in the neck places the cervical spine at increased risk for injury and degenerative changes. The cervical spine is also a common source of radicular pain in the shoulder. For this reason, the neck should be evaluated as a routine part of every shoulder exam. …

1Wolfson Centre for Age-Related Diseases, King's College London, University of London, 2Department of Neuroimaging, James Black Centre, Institute of Psychiatry, King's College London, University of London, 3Institute of Neuroscience and Psychology, Wellcome Surgical Institute, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, 4Research Service, Edward Hines Jr. VA Hospital, 5Neurology Service, Edward Hines Jr. VA Hospital, 6Department of Molecular Pharmacology and Therapeutics, Neuroscience Research Institute, Loyola University Chicago, 7Department of Oncology, The Gray Institute for Radiation, Oncology and Biology, University of Oxford

Balance and coordination are critical components involved in the control of movement. Many sensory receptors and neural processing units are required to help individuals maintain balance while performing various activities. Deficits in balance and coordination occur in patients suffering from movement disorders or due to aging. Therefore, scientists are trying to understand the pathophysiology behind these conditions. One way to do that is by using rodent models and testing them on behavioral paradigms such as the rotarod or balance beam.
This video discusses the currently known neurophysiology behind balance and coordination. Then, we go over protocols to run balance tests in rodents using the rotarod and balance beam. Finally, we'll discuss some current studies utilizing these methods to investigate aging, muscular dystrophy and Parkinson's disease.…

A fundamental requirement of biomedical research is the proper identification of research animals. It is essential that the right animal is utilized for procedures and data collection. Laboratory mice and rats can be identified with the following permanent methods: ear tags, ear punch codes, microchip implantation, tail tattoos for adult mice, and toe tattoos for neonates. Temporary methods of dyes and marking pens can also be used for acute studies. This video covers the technical aspects of ear tagging and punching for mice and rats, as well as the benefits of each with respect to the type of research being conducted on the animals. Knowledge of the basic manual restraint techniques for each animal (covered in a separate video) is required for these identification methods to be properly accomplished.…

1Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Biopolis, 2Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 3Lee Kong Chian School of Medicine, Nanyang Technological University, 4Centenary Institute for Cancer Medicine and Cell Biology, 5Discipline of Dermatology, University of Sydney, 6Department of Dermatology, Royal Prince Alfred Hospital, 7LSI Immunology Programme, National University of Singapore, 8School of Biological Sciences, Nanyang Technological University

Abdominal pain is a frequent presenting concern in both the emergency department and the office setting. Acute abdominal pain is defined as pain lasting less than seven days, while an acute abdomen refers to the abrupt onset of severe abdominal pain with features suggesting a surgically intervenable process. The differential diagnosis of acute abdominal pain is broad; thus, clinicians must have a systematic method of examination guided by a careful history, remembering that pathology outside of the abdomen can also cause abdominal pain, including pulmonary, cardiac, rectal, and genital disorders.
Terminology for describing the location of abdominal tenderness includes the right and left upper and lower quadrants, and the epigastric, umbilical, and hypogastric regions (Figures 1, 2). Thorough examination requires an organized approach involving inspection, auscultation, percussion, and palpation, with each maneuver performed purposefully and with a clear mental representation of the anatomy. Rather than palpating randomly across the abdomen, begin palpating remotely from the site of tenderness, moving systematically toward the tender region, and thi…

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JoVE (Journal of Visualized Experiments) is the world’s first PubMed-indexed scientific video journal. Its mission is to advance scientific research and education by increasing productivity, reproducibility, and efficiency of knowledge transfer for scientists, educators, and students worldwide through visual learning solutions.